ylides derived from short-chain trialkylphosphines in the Wittig-type olefinationreactions toward the synthesis of alkenes, including stilbenes, styrenes, and 1,3-dienes, as well as reagents for homologation reactions, are described. The methods allow easy access to alkenes with high (E)-stereoselectivity in good yield. These reactions are conducted with weak bases in aqueous media, which allows easy
Highly Stereospecific, Palladium-Catalyzed Cross-Coupling of Alkenylsilanols
作者:Scott E. Denmark、Daniel Wehrli
DOI:10.1021/ol005565e
日期:2000.2.1
[reaction: see text] Alkenylsilanols bearing methyl ((E)-1 and (Z)-1) or isopropyl ((E)-2 and (Z)-2)) substituents are converted to disubstituted alkenes by a palladium(0)-catalyzedcross-coupling reaction with aryl or vinyl iodides in the presence of tetrabutylammonium fluoride or hydroxide. Yields and stereoselectivities are generally high, and the reaction is compatible with a wide range of functional
Stereospecific Palladium-Catalyzed Cross-Coupling of (<i>E</i>)- and (<i>Z</i>)-Alkenylsilanolates with Aryl Chlorides
作者:Scott E. Denmark、Jeffrey M. Kallemeyn
DOI:10.1021/ja065988x
日期:2006.12.1
geometrically defined (E)- and (Z)-alkenyl- and styrylsilanolates with a wide variety of aromatic and heteroaromatic chlorides has been achieved. Under catalysis by bulky, biphenyl-derived phosphines and allylpalladium chloride, the (preformed, stable) potassium salts of di-, tri- and tetrasubstituted alkenyldimethylsilanols undergo high yielding and highly stereospecific coupling to aryl chlorides in THF or dioxane
REDUCTION OF ORGANIC COMPOUNDS WITH LOW-VALENT NIOBIUM (NbCl<sub>5</sub>/NaAlH<sub>4</sub>)
作者:Mitsuyoshi Sato、Koichiro Oshima
DOI:10.1246/cl.1982.157
日期:1982.2.5
Carbonyl compounds have been deoxygenatively dimerized to alkenes with the title reagent. Deoxygenation of epoxides to alkenes, reductive coupling of allylic and benzylic alcohols to hydrocarbons, and reduction of alkynes to alkenes are also described.